The present invention relates to a control device for an automatic vending machine, and more particularly, to an automatic reset mechanism for the control device of an automatic vending machine.
In recent years control of vending machines has been accomplished by providing a digital control device including a central processing unit (hereinafter referred to as a CPU). The CPU controls the dispensing and sales operation of the vending machine as well as recording useful sales information such as total amount of sales, amount of sales for each product, etc. However, due to various factors, the CPU may be caused to "runaway." The runaway condition may be caused by, e.g., failure of a mechanical system, noise causing an erroneous control signal, ect.
Such a runaway condition may be corrected to either manual or automatic reset of the control system. However, in the case of an automatic vending machine, manual reset is impractical. Therefore, it is necessary to provide an automatic reset mechanism for resetting the control system. Typical automatic reset mechanisms rely on monitoring the CPU operation for a predetermined time period to detect a runaway condition. These systems, however, suffer from the disadvantage of a time delay which is necessary to detect the runaway condition. As a result of this delay, it is possible that the control system may not be properly reset. Further, it is possible that the CPU software be reset and nonetheless the automatic vending machine will be inoperative due to the delay necessary to detect the runaway condition.
To resolve the above-mentioned disadvantages, it is desirable to provide a system wherein the time necessary to detect a runaway condition is minimized.